Electrical measuring instrument



' May 31,1927

' 1,630,908 W- M. SCOTT ET AL ELECTRICAL MEASURING INSTRUMENT Original Filed Jan. 7, 1922 2 Sheets-Sheet 1 Mai 31, 1927. 1,630,908

w. M. SCOTT ET AL ELECTRICAL MEASURING INSTRUMENT Original Filed Jan. '7, 2 Sheets-Sheet 2 .tlriinalaiifili cation fiIed JanaaryEZi922, Serial No. 527,552., Divided and j I i aiee i mseriaiiw. 691,385.

Feten'ted May 31, FEB? This 'inventioii' relates to electrical measuring"instruments and. has particular refer- ?act'er xvhichfshall consist offa niinimumnum-j simple in "construe tion, inexpensive to manufacture and easily". I p p "base for. said 'niemberg' A support 8; is

:ence to an-ainineter of the'typeused on self propelled'vehicles for indicatinglthe rate of ,fiO\V of current to andlfrom the. starting 7 and lighting battery;

The principal ob ect ofjthe presentinvention is to provide an instrument ofthis char.-

ber of parts which are p and quickly assembled. I

Another object is to provide an instrument of this character which shall be ruggedand capable of withstanding the extreme v braare subjected,

tionstolwhich such instruments and'yet' be capable of indicating accurately the rate ,of current flow to and from the battery 1- I "A still further obj ect islto provide an ammeter which shall be so constructed andass e nbled as to reduce to a ininimnin the possibility of incuri'inga short circuit therein.

VVit-h these various objects in view and: others which Will become appare-ntas thede the invention consistsin scription proceeds,

the novel features of construction and'in the manner of combining or arranging the samef; i

slightly and is provided abo-utitsperiphery .all of v'vhichv willbe frilly described herein- In the accompanying drawing, Fig. 1 is a front elevation of our improved amineter;

Fig. 25s a rear elevation of the assembled" flO j nor of supporting the bridge from the frame f and casing; and Fig. 11 1s a detail in section" operating mechanism .ofthe am'ineter and showing'the sameremovedifrom the casing; Fig-. 3 is a side elevation of the partsshown p p *which' shelves receive a an insulating- I bridge in Fig.2; Fig. 4 is a sectional view taken on the line 4- of Fig. 5;.Fig. 5' is central transverse sectional view through the instru ployed in our instrument; Fig. 8. is a per spective view of a supporting member form-f ing part of the instrument; Figs. 9 and 10'. H Fig. 5) to prevent rotationthereof when said perspective of a modified man are details in showing a inodifiedmanner of "fastening the clialtothebase. p, f j" Describing by referencecharacters the various parts illustrated, 1 indicates a dial in the form of a circular disk which is preferi l e recesses 18; 1 Figs. 3,11 and 12) of the instrument; Fig. 7 is a bridge to the saic'larmS- from sheet metal and provided ELECTRICAL mnasnniite l wman I on one face thereof ivithj a c'alibrate'd i'scale,

indicated at 2'. Secured' to this j'disln lon the rear side thereof, is'la, sheet inet alsuppoftingnieinberfi Which "is shown in' detail in Fig; 8. This supporting member comprises "-abase having air'ai'm 5 projecting-upward- 1y therefrom at each end. -Each' ai'nrisprcvidedwithan ear Gstain'pied therefrom, said earslying in the planeof the base eandreceiving screws 7 which fasten the supporting member to'jthe disk, the disk constituting a struck upfroin the base 4;, the upper portion of said support being bent over parallel-With thebase, as shown zit-8*, the base andthe part 8 serving to -receive andpivotally'support' staff 9 has mounted thereon' an" armature '11 and a damping device 12,said-da-mping device b'einglocated inor adjacent-to a point the staff .9 of an indicating needle 10. -The' ofhigh concentration-of a permanent niagnet field which tends to. resistrapid-and vibratory movement of theneedle and the device and locatedin the inaxiinuinfieldof a The opening in the base,

armature 11 beingspacedfrom said d m i v 'current coil-to be referred to-hereinafter.

formed byjpunch 1 ing the needle support therefromfie enlarged i with a plurality of clips13 enabling the peropening from theunder side'of'the'basegand to be retainedfinposition bywthe clips -13,

' when the parts are assembled.

17 ,the'ends 16 ofeach shelf beingibent up W ardly and inwardly to *form clips" entering forined in I the said bridge see thereby to secure said; 1 The insulating bridge is provided WithfltWo apertures19-ar- 'n'ianent inagnet-l lto be insertedinto saidl {ranged inspaced relationship and adapted i to receive terminalscrews"2O Which'arepref erably providedjwith anchoring fins 21 (see screws are pressed into 'tlle said apertures,

the finslf orming their own seats in the insulating materiallot the bridge, which inay be, of fibre; or other insulation. These screwsserve as terminals forv the meter and the "ends suitableinanner, as bysol'deringr I convolution 24 and a convolution 25 spaced apart and connected by an intermediate portion 26, the. convolutions 24: and 25 being spaced apart and arranged substantially as shown, It will be noted. that t'he'pernianent magnet 14, current coil 22, and .the'movable I I system cjomprisingthe staff 9,. needlev 10, ar-

mature .11 and damping "device 12 are grouped'and arranged so' that the current coil-lies wholly to one, sideof'the permanent magnet with its field para llel to the magnet .f magnet.

face and 'substantially perpendicular .to' a [line joining the magnet' poles. Also the staff 9 ismounted so as to intersect the cu'r- .ren't coil and its axis s perpendicular to the tiOns the armature 11 in the maximum field Iof the currentwcoil and out of the maximum field of the permanent magnet, whichca'uses 5, more nearly equal effect by the two fields than has heretofore been accomplished in ins-truments of this .type, and a more uniform .*,scale is obainable togetherwith remarkable accuracy. 7

The dial," supporting member, and associated parts, fo rm1ng an assembly 3 such as shown in Figs 2 and 3,.arenext placed in a casing. This casing'is composed of a rear.

' portion 30 and a front portion 31. having a transparent pane positioned therein. The rear portion 30 18 provided w th two en- .larged apertures 33 through which the terinin'al screws 20 projectloosely, and an in-' vwardly'directed tongue 34cis punched from the casing adjacent to and intersecting "the periphery-, -of each aperature 33,

cesses 35, 35. in the insulatingbr idge (Fi 7) as clearly shown vin'Figi 5, and thus position the terminals 20 centrally with respect. to the aperturesg33. This arrangement also. 5 prevents themovem'entof the terminals with respect to the casing and hence prevents the rear portion of the casingfrom contact ng electrically with, the assembly positioned;

' therein, due -to the large air gap provided around each terminal- Before the assembly is positioned in the rear. portion of the casing, an apron 36. (Fig.

6) of insulating material is slipped over] the terminals 20 and into contact with the insulating bridge, having apertures 36 for the reception of saidtermmals,andend recesses 36 for the reception of the tongues. 3&1. Thisiapron'malres--short1ng impossible between the clips 16Tand the casing. and be tween'the coil and the casing, even should I the coil become displaced, as by violent treatment,or by overheating,in such a manner as; to touch the base or (but for such apron) to.

The I I tongues 34: are adaptedto enteraligning. re-

touch'the back of the casing When. the complete assembly has been positioned in the rear portion of the casing, and'the tongues 34L are entered inthe reeessesfifi i-and" 35, as 1 previously described, then .an insulating ,1,- washer 38 is slipped over each terminal and into contact with thecasing, afterwhich a.

nut 39' applied to each 'terminalto" draw the parts up tightly.- Any suitable'transparent front 1n1ay be applied to the'rear por 5 tion of the casing, as for 'example,fa' front similar to. that disclosedin, our coo-pending application Serial No. 527,552,iiled January .7- 1922. 1 I v a In Figs. -9 and 10 there is shown ainodifi-edmanner of holding the insulating bridge and of centering the same with respect to the apertures 33 in the baclcof the casing. In these views, the bridge" 17? isimade of j relatively soft or yieldinginsulating material, such as fiber and isprovided with holes 35, which may be bored therethrough, for" the reception of the tongues 34'. Because formed, no side recesses need be preformed in the ends thereof, but the ends of the clips 16fare pressed into the sides of the ends so as to be substantiallyflush with the top.

and the sides of thejbridgei Thisreduces the cost of mounting and assembling.

j In 11 there is shown a. modified manof the material ofwhich the lbridgefis I ner of supporting the disk. from the base 4:.:'

Instead of usingscrewsi integral heads 7 are struck from the. base and project into holes 7 in thefdisk, the heads being spread out, as by means of a center punch, so that the sides of the heads will engage the side walls of the cooperating holes or apertures,

thereby to secure. the disk to 'thebase.

Having thus described our invention, what we claim w 1 1. In an apparatus of the character set forth, the combination with a disk, of a supporting member a for, said disk, an; in-

sulatingbridge carried by said supporting member, a needle support projecting from said supporting member, aperm'anent magnetnponsaid supporting member,"a movable system .journaled between said needle support and said supporting"member, apair .of'terminals carried by said"br1dge,and a current. coil having the ends thereof electrically connected to said terminals and disposed in operative relation to said movable system.

2. In an apparatus of the character set forth, the combination, with a base, of a pair ofarms projecting from said base, an insulating bridge carried by'saidarms, a support overhanging said base," a movable-system ournaled between said support and said base, a permanent magnet interposed betweensaid support and said base and havmg the poles thereof disposed in operative relation to Said movable system, a pair of 1 3 terminals carriedby said bridge, and a cur- .rent coil having the ends thereof electrically connected to said terminals anddisposed in operative relation to said movablesystem;

3. In an apparatus of the'character'set forth, the combination, ivitha disk, of a supporting member for said disk and haV'-' ing a pair of arms projecting upwardly from said member, an insulating bridge carried by said arms, a needle support :t'ormedintegral with and pro ect1ng from the base of said member, a movable system able system. a

4. In an apparatus of the character set.

journaled between said needle support and said base, a permanent magnet interposed between said'd sk and saidbase and having the poles thereofdi sposedin operative relation to said. movable systems, a'pair of ter: minals carrled by said-insulatmgbridge,

and a current coil having the ends thereof electrically connected to saidterminals and disposed in operative relation'to said movforth, the combination with ameter assemi 'to center said. terminals in said apertures.)

5. In an apparatus of the character vsetbly including a dial and a supporting member secured thereto, of an insulating bridge carried by said member and having a pair of terminals projecting therefrom, a casing adapted to receive said assembly and prow vided with a pair o'f'enlarged' apertures adapted to receive said terminals loosely therethrough, and means carried by said casing and adapted to engage said-bridge forth," the'combination, with a meter assem-' bly including a disk and a supporting memsecured to,said.arms,a1id a said member and having apair vof terminals projecting there'from'," arcasing adaptedtofrece ve said assembly, sa1cl-cas1ng -be1ng pro;

1 re y; of a bridge time by; I

vided with a pair of: enlargedfiapertures' {6; A" sheet metalsupporting said base and extending therefrom, the outer ;end of said needle support'being bentigo' ven parallel w thsald ba-se, said base 'being prov-lded WVltll an aperture therein for receiving:

a permanent magnet, and means associated with said base for retaining. said aperture.-

7. The combination, with a base, ofa pair" of arms projectingtherefrom, a needle sup- }port struck from said base and extending therefrom, theouter end of sa d needle 'supa member for aninstrun'ient of the character set forth comprising a base, a'pairof arms project- "ing therefroima needle support struck from said magnet in I port being bent over parallel ithsaid.base,'

said base being provided with an aperture, (therein for receivmg a permanent magnet,

means; associated With said base tor retaining said magnetin said aperture, a bridge carried by said bridge. a i

In testlmony whereof, we hereunto afiix our signatures. 1 V

I WALTER M, SCOTT' RALEIGH E. TRESISE.

pair of terminals 

